Artificial leg



I. P. KNUDSEN.

ARTIFICIAL LEG.

APPLICATION FILED .MAY II, 1920.

Patented A191219, 1921.

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JENS PETER KNUDSEN, 0F KIEDEBY, DENMARK.

ARTIFICIAL LEG.

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Specification of Letters Patent.

Patented` Apr. 19, 1921.

y Appiieation ined nay 11, 1920. I serial No. 380,491.

The heretofore known artificial limbs are but slightly bent in withdrawn position, and the foot, when relieved of the weight of the body, is essentially at right angles to the lower leg. ln order that the limb, in such withdrawn position, can freely swing forward, without touchingthe ground, and that the wearer does not waddle too noticeably, it has to be shorter than the natural leg.

W ith the present invention the artificial limb is equally as long as the natural limb, and waddling of the wearer is avoided by the said artificial limb, when in withdrawn position, being more bent at the knee than was the custom with such limbs heretofore, and by the-point of the foot, when swinging forward, bending upward, so that the withdrawn limb may freely swing forward without there being any danger of its striking the ground.

ln the accompanying drawing the improved artificial legis shown in side elevation and partly in section.

The limb shown in the drawing is intended for patients, when the natural limb has been amputated at the hip. rlhis leg consists of the following parts:

i leather bandage L, which is strapped tightly around the loins and the hip, an upper leg or thigh limb 0, a lower leg or calf limb U and a foot F. These parts are connected to each other by means of three hinges, viz, one at the hip, one at the knee and one at the foot-joint or ankle. The axis of the hip and footl joints are practically parallel to Yeach other whereas the axisrof V v maintain the form of the bandage and also the knee joint is, although also horizontal, disposed obliquely to said axis, so that when the lower leg is being withdrawn, it 'isy first guided obliquely toward outside, so that ythe danger that the foot,'when being swung forward, knocks againstthe ankle of the natural leg,;is reduced. rlhe leather bandage L is fitted with steel bands', which serveto to hold the hip joint H. To the lower edge of the leather bandage L is attached a circular curved flat steel band Z), which, when the bandage is fitted, rests in a groove c cors responding to the band ZJ and provided in the top surface of the upper leg 0. To the top of the upper leg on its outside surface is attached a fitting 30 (shown broken oi in the drawing), by means Vof whichl the upper leg is pivotally hung to the axis H of the hip. .This fitting is provided with a cam 37, which, when the upper leg is moved backward, will bear against a stop 38 on vthe'bandage fitting, so that the backward stroke of the upper leg in the hip joint is limited.

Through the vupper leg is passed a spindle 9, on which tilting lever 10 is pivoted. By means of a spring 17 this vlever is obliged,

`in known manner, yto assume either of two ex reme positions. The endsl of the said lever are connected by means of metal cords and 3 to screws 39 and 40. The cords 7 andB extend beyond the lever downward to two pawls 1 and 2, fitted on an axis 34 farther down in the upper leg. rlhese pawls 1 and 2 alternately engage with two ratchet wheel sectors 3 and l, turning on the knee joint axis K. rlhepawl 1 is held down toward the ratchet wheel sector 3 by means of a spring 1,1, buty at such a distance from said ratchet wheel, that the latter may turn freely clockwise without any rattling noise being produced by the teeth of the wheel scraping along the pawl. 1When turned contrary to clockwise a flat spring 12, which issecured to the pawl 1 and bears tightly against the ratchet wheel 3, will bring the pawi 1 into engagement therewith and there by prevent the turning of said wheel sector; a similar arrangement is provided for pawl 2 with reference to ratchet wheel 4. The ratchet wheel .3 is coupled by means of a coiled spring 14 to the lower leg U. Rubber stops 19 and 29 limit the swing of the ratchet wheel sectors.

The lower leg U is made of wood and hollow, and is at the top provided with bearings for the knee joint axis K and a recess for the ratchet wheels 3 and 4; below are provided the bearings for the foot joint axis A and an axis 4:1, on which is fitted a pawl 5 the tooth of which is in engagement with a lug 18 on a lever 31, swinging on the foot joint axis A. The point of the foot is not at right angles to the axis A, but oblique to V"io the same (the heel pointing inward); the reason for this arrangement and the advantages derived thereby shall hereinafter be specified.

The pawl is connected by means of a Ycord 42 to a screw 43 on the ratchet wheel Y sector 4; when the lower leg swings forward, relatively to th J upper leg, it is obvious that as soon as the ratchet-,wheel 4 is held by the pawl 2, the cord 42 will be drawn taut and will release the lug 18, and the elastic band 16 which connects the instep of the foot to the lower leg will bend the toe-.part upward. The foot is hinged to the lower leg by means of a fitting 44, which passes under the foot and extends upward on both sides thereof.

@nan axis 45 inthe lower leg is pivoted i a bell-crank V, the one 'end 6 of which may the body over the foot.

engage a stop 32 secured in the foot.V This engagement occurs, when the weightof the body rests on the toes, by aid of spring 33.

To the horizontal arm of the bell-crank VV y is attached a cord 46 which is passed through a piece of tubing 47 'to a screw 48 on the outside of the upper leg, abovey and in front of the knee axis K. When the knee is bent,

apull will be exerted on the cord 46, where- Y by the pawl 6 is disengaged from* the stop l vOn lever 31 act twov strong springs 15, one on each side, and betweenV the heel and the lower leg are inserted two springs 2O of Ywhichfrvonly one'is to be seen in the drawing,

which springs are placed under tension,

whenla load bears on the heel;

VTo the heel is attached by means of an adjustable screw 35 a cord 51, to which a lug 49 is soldered, which, by abutting against 'a-tubular stop 50 limits the upward turn 'Y of the toeV and distributes the pressure of The cord 51 isV secured to a forkedbearing 52, which by means of a sheave and rope pulls a spring 13 by a distance which is twiceas long as the stroke of said forked bearing itself. The saidl spring 13 -is secured by Vmeans of, a screw 36 to the outside of the yupper The backward swing of the lower leg, Vrelativelyto the foot is limited by stops 27 and 28 on the lower leg and the foot,'respec tively. ln front of thc lever 31 is provided a rubber stop `22 fitted into "the body of the foot', theV movement of whichis limited by the fixed stop 21.r `For the shorter armY of lever V31V is v,provided ariibber stop 25. The footpis made of wood,` with the necessary recesses for the parts mentioned, and is inclose'd in a leather boot. The toe is joined by aidof springs to theV main body of the 1lor nio'rel clearlyV explaining Sthe nature c of the present invention the operation ofthe artiiicialleg shall now be described.V V`V'rissumed the body is in forward move# ment; thenfthe artificial leg'will, at a givenV moment,ibe a position behind thev body, and the following will occur; the cord 7 is pulled taut, the lever 10 is swung over, the

' pawl l'i'sflifted and the pawl 2 is lowered.

The knee axis K, which is infront of the vertical plane through the hip vjoint H, is

pressed back until the stops 23 and 24 meet.

partly relieved. The spring 13, is therebyY able to bend the knee oint, while the point of theV foot presses tightly against'- the Y ground.' TiWhen the knee joint is bent so far that aline drawn through ll-l and K passes beyond the toe, the position of the screw 48 with referenceto the lower leg is changed in sucha manner, that a pull is exerted on cord 46, so thatfthe tooth 6 'disengages the spring 15 and the energystill 'storedV in 13, thus producing, while the leg is being bent, a setting off movement of the4 toe whereby the foot is lifted. When the lower leg is farthest turned backward relativelyV to the upper leg and then attempts to turnA forward "the pawl 2 will engage in the ratchet wheel 4, so that the lower leg cannot be turned forvioo ward relatively to the upper leg. rlhe gravV ity will now tend Vto draw the bent and lifted lower leg and/foot downward, but

thereby theV cord 42k will be tightenedV andY will disengage the pawl 5, and the foot will under action of the elastic'band 16, again move into its hookedL position, The knee is now greatly bent and the toe is pointing upward. Y The limb can, therefore, swing freely forward without there being any dan-V rer ofits knockingragainst the ground orthe ankle of the natural leg.V By the forward swing of the Vthus bentleg the cord 8 will be Y tightened and the lever 10 will be tilted over,

whereby the pawl 2 is lifted and the pawl 1 Vis lowered; the lower leg will then continue its movement aroundthe axis ofthe knee Y until the kneejis straightened out.

' rlhe lower legis prevented fromswiiiging back by being locked' in the forward*` Vstretched`r position Vby means ofl the pawlV 1 and the 'ratchet wheel sector 3. n The heel of the artificial Yleg is now placed on the'ground 'Y a little ahead of the center of'gravityof the body.V Bui-ing the last-forward swingjtheL spring 13 has, by pulling the cord 51 again moved the foot finto its normal position and the elastic band 16 isstretched, v'vhilethe pawl 5 is engaging the lug 18V'.V ,Then'body iso is now moved Jforward over the artificial leg n and the next lstep is commenced. i By the shown arrangement of the ratchet Wheel sector 3 in the lower leg it has been obtained that, as, the said ratchet wheel sector may turn a little in both directions on the axis, both heel and toe may step on stones, without the equilibrium being disturbed, as small turnings of the foot will be compensated by small turnings of the ratchet wheel sector 3 and by that, the lever 31 acts on the springs 15 or on the rubber stops 22 and 25. The pawl 1 will, namely, at a slight turnnot immediately engage the first tooth of the ratchet wheel sector 3; ii, for example,

the toe steps onto a stone, the consequence will be that the pawl 1 moves one tooth, orward in the ratchet wheel sector 3, so that the center of gravity of the body still remains in front of the plane of support; this cannot be obtained with limbs having a stili knee. If the heel steps onto stone, the pawl 1 will not advance, but the ratchet wheel sector 3v will be turned back, the spring 14 will, then, tighten and assist in stretching the knee when the leg is set forward. i

If the toe is very slantingly turned upward, the -tooth 6 will engage the stop 32 thus preventing, the springs 13 and 15 from bringing the-body out of equilibrium.

I claim:

1. Artificial leg consisting of a rigid hipbandage, an upper leg, means Jfor hingedly securing said upper leg to said hip bandage, a lower leg, means for hingedly securing the lower leg to the upper leg, a foot and means for hingedly securing the footto the lower leg, the hinge between the upper and the lower leg (the knee-hinge) being, at an upright position of the leg, somewhat in front of the vertical line through the hip-hinge and the foot-hinge, respectively.

2. Artificial leg consisting of a rigid hipbandage, an upper leg, means for hingedly securing said upper leg to said hip-bandage, a lower leg, means for hingedly securing the lower leg to the upper leg, a foot and means for hingedly securing the foot to the lower leg, the hinge between the upper leg and the lower leg (the knee-hinge) being, at an upright position of the leg, somewhat in front of the vertical line through the hiphinge and the foot-hinge, respectively, the axis of said knee-hinge, although likewise horizontal, the same as the axis of the hiphinge and the foot-hinge, being not exactly at right angles to the symmetrical. plane of the body, the toe of the foot pointing somewhat outward.

3. In an artificial leg composed of a hipbandage, an upper leg, a lower leg and a foot, a hip-joint consisting of said hip-bandage, steel reinforcements thereon, a Jointaxis supported therein, straps hinged therereinforcements, and in the upper end of the upper leg a groove, adapted to receive said flat steel band. V. v 1. In an artificial leg composed of a hipbandage, an upper leg, a lower leg anda ieoot, a knee-joint consisting of a joint-axis, to which upper leg and lower leg are hingedly attached, fitted on lsaid joint-axis two ratchet-wheel sectors, a pawl for each of said ratchet-wheel sectors, leach of said pawls coupled by a metal cord to said hipbandage, said cords intermediately attached to a tilting-lever, a spring, adapted to hold said tilting lever in either of two extreme positions, springs limiting the stroke of said pawls, abutments limiting the bend of the knee-j oint, the one of said ratchet-wheel sectors coupled by means of a coiled spring to the lowerleg.

5. In an artiiicial leg composed of a hipbandage, an upper leg, a lower leg and a foot, a foot-joint consisting of a joint-axis, to which the lower leg and the foot are hingedly attached, fitted on said joint-axis a double-armed lever, a pawl coupled by a metal cord to the free ratchet-wheel sector in the knee-joint and adapted to engage over the short arm of said double-armed lever', a coiled spring coupling the longarm of said double-armed lever to the body of the foot, abutments limiting the stroke of said double-armed lever.

6. In the foot of an artificial leg composed of a hip-bandage, an upper leg, a lower leg and-a foot, a heel-piece, said heel-piece coupled by means of a metal-cord, a pulleyvblock and an expanding spring to the upper leg, means for adjusting the length of said metal cord, on'said metal cord a stop, in

the lower leg an abutment, adapted to engage said stop on the metal cord and partly take up the weight of the body, a bellcrank lever hinged to the lower end of the lower leg, the one arm of said bell-crank lever adapted to engage against said heel-piece, the other arm coupled by means of a spring and aemetal cord to the upper leg.

7 In an artificial leg, a hip bandage, an upper leg portion connected thereto, a lower leg portion, a foot body attached to the latter, a toe piece connected by a compression spring to said foot` body, a heel piece on said foot body, a cord connected at one end to said heel piece, a pulley block on the other end of the cord, a flexible and resilient support connected at one end to said lower leg portion and passing about the pulley of said block and attached at its other endto the upper leg portion, a stop on said heel piece adapted to engage said lower leg portion for partly taking up the weight of the body, and movable means carried in thelower leg iio portion connected to the upperleg portion and arranged in the path of movement of said heel pieee for engageineiittherewith,

8. In an artificial leg, a'lower leg portion,

a `foot body pivoted thereto, and resilientY means connecting the instep of the foot to Vthelower end of said lower leg Vportion in tion,V afoot body pivoted to the lower endv f i5 of said lower leg portion, an elastic band 4 Yseeurecl at Vone end to the instepiof said footV body and at its other end'tosaid lower leg portion for normally urging the orepart of said foot bodyin an elevated position above that of the heel part,land a resilient, differential connection between the heel part oitl said foot body and said upper and lower leg'l portions. Y

In testimony7 that I olaiin'tlie` foregoing as my invention, I have signed my naine in 25 presence of two Ysubscribing witnesses.

IENS PETERKNUDSEN.

Vitnesses-z Y i P. HoiMAN-BANG, C; E., I-IENRY C. A. Dix-MM. 

